Polyols are valuable materials with uses such as PTA/PET, cold weather fluid, cosmetics and many others. Generating polyols from cellulose instead of olefins can be a more environmentally friendly and economically attractive process. Catalytic conversion of cellulose into ethylene glycol over supported carbide catalysts was disclosed in Catalysis Today, 147, (2009) 77-85. US 2010/0256424, and US 2010/0255983 teach a method of preparing ethylene glycol from cellulose and a tungsten carbide catalyst to catalyze the reaction. Tungsten carbide catalysts have also been published as successful for batch-mode direct catalytic conversion of cellulose to ethylene glycol in Angew. Chem. Int. Ed 2008, 47, 8510-8513 and supporting information. A small amount of nickel was added to a tungsten carbide catalyst in Chem. Comm. 2010, 46, 862-864. Bimetallic catalysts have been disclosed in ChemSusChem, 2010, 3, 63-66.
US2011/312487, US2011/312488, and US2011/0313212 describes conversion of cellulose to polyol using a process which involves contacting cellulose with a catalyst system in a reaction zone to generate an effluent stream comprising at least one polyol and recovering the polyol from the effluent stream. The effluent stream further comprises unreacted water and hydrogen and reaction intermediates which may be recycled to the reaction zone. The catalyst system comprises both an unsupported catalytic component and a supported catalytic component.
However, the above process does not describe the use of a ligno-cellulosic biomass, which up to know have presented problems as starting materials, primarily related to their highly viscous nature when presented as a slurry comprising solid ligno-cellulosic material and a carrier liquid. It has been documented that a solid presents significant handling problems, as described in PNNL-16079, September 2006, which states:
High-pressure feeding systems for biomass slurries have been recognized as a process development issue at least as long as the modern biomass conversion systems have been under development since the Arab oil embargo of 1973. The authors review the state of the art and various slurry pumping systems, the vast majority of which include ball check valves. Their conclusion is that high-pressure feeding remains a problem for small scale production but believe “the high-pressure feeding of biomass slurries should be more readily achieved at larger flow rates wherein the fibrous nature of the biomass would not be expected to bridge and plug the orifices and valves.
Thus, there exists a need to provide a low viscosity ligno-cellulosic biomass slurry composition which allows processing in a catalytic system for generating polyol. The mechanically thermally treated ligno-cellulosic biomass process described herein to produce a low viscosity ligno-cellulosic biomass slurry, as well as its subsequent conversion to polyol materials, also described herein, address this need.